I'm loading a similar load. The only difference is my charge of AA5744 is 28.0gr. That load is shot in both my Trapdoor and Marlin levergun.Thank you everyone for the help.
I have loaded and shot 4 3 shot test loads.
26 grains of 5744
Winchester large rifle primer
col @ 2.550
405 Grain .459 Flat Point Hunters Supply non gas checked.
No leading, the best group so far measures at 1.5 inches.
Shots have been made at 100 yards
Going to load a few more and keep trying.